The use of semiflexible anterior chamber intraocular lenses, widespread during the early 1980's, has been abandoned due to the many complications associated with their use. Patients who received these lenses currently represent the majority of patients with pseudophakic bullous keratopathy. We studied the morphologic characteristics of the corneal endothelium in 20 patients who had undergone extracapsular cataract extraction followed by anterior chamber or posterior chamber intraocular lens implantation. Specular microscopy and computer-assisted morphometry were performed preoperatively, 3 months postoperatively, and once a year thereafter. The follow-up period for each subject was 5 years or longer. The endothelial cell density of the central cornea in the anterior chamber lens group decreased from 304 to 196 (x 10 cells/mm2), and in the posterior chamber lens group decreased from 315 to 269 (x 10 cells/mm2). Four patients in the anterior chamber lens group developed pseudophakic bullous keratopathy 6 or 7 years after surgery. Severe endothelial cell loss and morphologic change were seen in patients who received anterior chamber lenses.